The heart pumps oxygen-rich blood into the arteries. When the heart beats, blood is supplied first to the aorta, and an aortic valve is located between the left ventricle and the aorta. This aortic valve opens and closes to control the direction of blood flow. It is open in particular during the systolic heartbeat to allow blood to flow into the aorta. During the diastolic heartbeats the aortic valve is closed, to prevent the return flow of blood into the heart. For various reasons, however, the aortic valve may be damaged and stenosed. If this occurs, the aortic valve does not open to its normal extent, and the blood flow from the heart into the aorta is impeded. This leads to a condition described as aortic valve stenosis.
Known from U.S. Pat. No. 6,746,463 B1 are a device and a method for the removal of such an aortic valve stenosis, in which a balloon catheter with a guide wire is arranged with the balloon in the area of the aortic valve. The balloon catheter is then inflated. The balloon catheter has cutting blades which are braced radially during inflation. The cutting edges of each blade cut into the aortic valve and remove any stenosis which has formed on the aortic valve.
Known from WO 03/089041 A1 is a device for minimally-invasive intravascular or intravasal aortic valve extraction within the aorta of a human heart. This device is intended to improve the minimally-invasive intravasal extraction of the aortic valve, with complete exclusion of the risk of embolism due to tissue and/or calcium particles which may enter the blood circulation system. It should moreover be possible for the surgeon to remove diseased areas of the heart valve individually, locally and selectively, and this preferably under direct visual observation of the diseased areas of the heart valve. For this purpose the device is in the form of a perfusion catheter which provides at least one perfusion passage and at least two dilation units spaced apart over the length of the catheter in the proximal catheter zone. The perfusion passage passes through both dilation units which in the inflated state form a seal, at least virtually fluid-tight, with a vessel wall, preferably the aorta wall. At least the distal side dilation unit should be provided with at least one through passage, through which at least one auxiliary catheter for aortic valve open blocking may be passed with fluid-tightness, and/or the perfusion catheter provided at least one operating passage with an exit opening in the area between two dilation units, through which the auxiliary catheter or catheters may be passed for the aortic valve open blocking. By means of the perfusion catheter, which substantially encompasses a hollow passage, a flow of blood should be ensured through the hollow passage, so that the surgical intervention is made on the beating heart, without impairing the heart's activity. The two dilation units are inflated on the heart side and the aorta side, bounding the aortic valve between them, and forming a fluid-tight seal with the respective vessel wall. Operations on the aortic valve are conducted in the operating space bounded by the two dilation units and the hollow passage, via separate access to the operating space.
A synthetic aortic valve is known e.g. from EP 1 335 683 B1. Other implantable heart valve prostheses, together with catheters for the implantation of such heart valve prostheses, are disclosed by EP 592 410 B1, US 2004/0210304 A1, U.S. Pat. No. 7,018,406 B2, WO2006/127765 A1, US 2003/0036795 A1, U.S. Pat. No. 5,411,552, U.S. Pat. No. 6,168,614 B1, U.S. Pat. No. 6,582,462 B1 and WO91/17720.
From WO 99/23976 it is known that in the removal of a stenosis, for example using a balloon catheter, the material causing the stenosis is dissolved, flows away with the arterial blood and, if it is large enough, may close a blood vessel and possibly cause a heart attack. For this purpose it is said to be known that filters may be placed in human blood vessels, to trap such embolism-causing material. It is also said to be known that removable filters may be used for this purpose. Such removable filters usually involve a filter of the umbrella type which has a filter membrane located on a folding frame on a guide wire. With this device it is said to be a drawback that, on folding together of the filter, the material which causes an embolism tends to be pressed outwards and re-enters the bloodstream.
Known from WO 0067688 is a further filter element with a folding filter body, which may be moved between a folded position for movement through a vascular system and an unfolded position to extend in a blood vessel so that blood flowing through the blood vessel is guided through the filter element. A distal inlet zone of the filter body has one or more inlet openings which are so dimensioned that blood and embolism-causing material are able to enter the filter body, and a proximal outlet zone with a multiplicity of outlet openings which are so dimensioned that blood may pass through but embolism-causing material is retained. The filter body is at least partly a laminate structure with a membrane provided with a bio-compatible coating. The thickness of the coating is 4 to 40% of the thickness of the membrane.
U.S. Pat. No. 6,676,683 B1 discloses a filter catheter which has at its end section an extending and expanding filter. The catheter itself is a guide wire along which further catheters, which encompass this guide wire, may be guided for suitable positioning in the blood vessels.
EP 980 278 B1 discloses a similar catheter with a guide wire, at the end of which an expandable filter element is provided.